This invention relates in general to improvements in internal combustion engines and, more specifically, to an improved cylinder head and piston arrangement with an improved valve and spark plug layout for use in those engines.
A great many different intake and exhaust valve arrangements have been developed over the years for use in internal combustion engines, in particular for use in automobiles. Most such engines use one intake valve and one exhaust valve at each cylinder with a single spark plug. The prior art arrangements utilize exhaust area/intake area in the range of over 65%. A great deal of effort has gone into optimizing the sizing and placement of the valves, the shape of the combustion chamber and the like. Since there is a great need for improvements in automobile fuel efficiency while maintaining or improving performance, a wide variety of different valve and spark plug configurations and arrangements have been designed and tested. In some of these, multiple valves and spark plugs have been used.
An arrangement of four valves per cylinder, two intake valves and two exhaust valves, has been disclosed, for example, by Akana in U.S. Pat. No. 3,411,490. Today, a number of high performance automobiles use four valve systems, with one or more spark plugs.
In these high performance automobiles, several spark plugs may be provided around the periphery of the combustion chamber with an additional spark plug centrally located. Manufacture and operation of these four valve, multiple spark plug engines is complex and expensive and requires complex computer control for efficient operation.
Weslake in U.S. Pat. No. 2,652,039 describes a complex cylinder head arrangement for an internal combustion engine having a wedge-shaped combustion chamber adjacent to the cylinder feeding into a cylinder chamber above the piston. The combustion chamber has an intake valve, an exhaust valve and a single spark plug. A second intake valve is provided in the cylinder chamber. A weak mixture of air and fuel enters the combustion chamber, combustion begins and a rich mixture enters through the cylinder chamber and adds to the original combusting mixture. This very complex system appears to have been unsuccessful and to never have been brought into production.
Another three valve system is described by Von Segern et al in U.S. Pat. No. 3,443,552. Here, a basically conventional cylinder head having a single intake valve and a single exhaust valve with a primary, conventional, combustion chamber is provided. In addition, a centrally located auxiliary chamber is located on the cylinder axis away from the cylinder in gas flow communication with the primary combustion chamber. The auxiliary chamber has a single intake valve and a spark plug. Combustion begins in the auxiliary chamber, spreads to the main combustion chamber where added fuel mixture is introduced. Again, this is a complex and cumbersome system that appears to have been found to be impractical.
Suzuki et al. in U.S. Pat. No. 4,742,804 discloses a number of combustion chamber configurations, including some having two intake valves and a single exhaust valve. However, this arrangement requires that the exhaust valve be considerably larger than each intake valve and provides for a localized deep recess in the piston head to receive the spark plug. The combustion chamber is in the piston, rather than in a space between a generally planar piston face and the head.
Thus, while a great number of different arrangements of multiple valves and/or multiple spark plugs have been designed, none have provided an optimum combination of structural simplicity, maximum fuel efficiency and highest performance. Despite the crowded nature of the automobile engine fuel and air introduction and exhaust removal art, there remains a continuing need for improvements providing greater overall efficiency at lowest cost.
It is, therefore, an object of this invention is to provide a simple, easily manufactured internal combustion engine combustion chamber system having increased operating efficiency. Another object is to provide such as system that provides both increased fuel efficiency and higher performance. A further object is to provide such a system with high thermal efficiency. Yet another object is to provide a system capable of operating at high compression ratios with a variety of different fuels.